SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '50943850bf625711c1f1b548357cf5d5d9dca1f25261a143c6841c7c7eb23640' 
  AND token = 'dQsIisk5cHyveTAJNqHqxen8hnbBQlGErasQ5maogiA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}